Hi,
On 12/21/19 11:03 PM, Tom Murphy wrote:
@@ -5618,9 +5583,13 @@ static int intel_iommu_add_device(struct device *dev)
struct iommu_domain *domain;
struct intel_iommu *iommu;
struct iommu_group *group;
+ u64 dma_mask = *dev->dma_mask;
u8 bus, devfn;
int ret;
+ if (dev->coherent_dma_mask && dev->coherent_dma_mask < dma_mask)
+ dma_mask = dev->coherent_dma_mask;
+
iommu = device_to_iommu(dev, &bus, &devfn);
if (!iommu)
return -ENODEV;
@@ -5640,7 +5609,12 @@ static int intel_iommu_add_device(struct device *dev)
domain = iommu_get_domain_for_dev(dev);
dmar_domain = to_dmar_domain(domain);
if (domain->type == IOMMU_DOMAIN_DMA) {
- if (device_def_domain_type(dev) == IOMMU_DOMAIN_IDENTITY) {
+ /*
+ * We check dma_mask >= dma_get_required_mask(dev) because
+ * 32 bit DMA falls back to non-identity mapping.
+ */
+ if (device_def_domain_type(dev) == IOMMU_DOMAIN_IDENTITY &&
+ dma_mask >= dma_get_required_mask(dev)) {
ret = iommu_request_dm_for_dev(dev);
if (ret) {
dmar_remove_one_dev_info(dev);
dev->dma_mask is set to 32bit by default. During loading driver, it sets
the real dma_mask with dma_set_mask() according to the real capability.
Here you will always see 32bit dma_mask for each device.
Best regards,
baolu
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